Tropical
Highlights – February 2012

La Niña weakened during February 2012 as reflected
by the development of positive sea surface temperature (SST) anomalies in the eastern
equatorial Pacific and by a decreased magnitude
of the negative SST anomalies in the central equatorial Pacific (Fig. T18,
Table T2). The latest monthly Niño indices were -0.7°C for
the Niño 3.4 region and +0.2°C for the Niño 1+2 region (Table
T2, Fig. T5). Consistent with these conditions, the
oceanic thermocline (measured by the depth of the 20°C
isotherm) remained shallower than average in the east-central equatorial
Pacific (Figs. T15, T16), although corresponding sub-surface temperatures
were only 1-3°C below average (Fig.T17).
These departures are several degrees warmer than the large negative values seen
during November-January.

Also during
February, the equatorial low-level easterly trade winds were stronger than
average over the central and west-central equatorial Pacific (Table T1,
Fig. T20).Convection remained suppressed in the western
and central equatorial Pacific and enhanced across the Indian Ocean and the
Philippines (Figs. T25,
E3). Collectively,
these oceanic and atmospheric anomalies reflect a weakening of La Niña conditions.

For the
latest status of the ENSO cycle see the ENSO Diagnostic Discussion at:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.html